Direct synthesis of Cerium(Ⅳ)-Incorporated mesostructured cellular foam for immobilization of penicillin G acylase

Abstract

Cerium-incorporated mesostructured cellular foams (Ce-MCF) as a novel support has been synthesized successfully for immobilizing penicillin G acylase (PGA) through a Lewis acid-base interaction. The PGA was firmly immobilized on Ce-MCF by interacting with the surface robust Lewis acid sites due to the incorporation of Ce, which is the essence of this immobilization method. The Ce-MCF support was synthesized through the direct hydrothermal synthesis technique with citric acid complexant and categorized by XRD, SAXS, nitrogen sorption, XPS, TEM , and pyridine-IR. The results showed that the Ce-MCF samples had ordered long-range structure, large pore diameter, large specific surface area, pore-volume, narrow pore diameter distribution and strong Lewis acid site. According to the results, the PGA/Ce-MCF has high enzymatic activity and improved operational stability greatly. The PGA/Ce-MCF's initial enzymatic activity remains 10,573 U/g to hydrolyze penicillin G potassium salt, similar with that of PGA/Si-MCF. In addition, the Ce-MCF samples have much higher operational stability than PGA/Si-MCF. Followed by recycling for 10 times, PGA/Ce-MCF preserves 90% of its primary enzymatic activity, which is much higher than 77% of PGA/Si-MCF. A novel immobilization method has been developed for penicillin G acylase (PGA) by a Lewis acid-base interaction. The essence of this method lies in utilization of a Ce-MCF (mesostructured cellular foam) nanoporous material. The cerium incorporated into the framework of MCF can significantly enhance the Lewis acidity of MCF. The high operational stability and enzymatic activity of PGA/Ce-MCF achieved during the hydrolysis of penicillin G potassium salt, suggesting that the enzymes can be firmly immobilized by the Lewis acid sites whilst retaining high activity. • PGA can be firmly immobilized on Ce-MCF by the Lewis acid sites whilst retaining high activity. • After recycled for 10 times, PGA/Ce-MCF retains 90% of its initial enzymatic activity, much higher than 77% of PGA/Si-MCF. • The cerium incorporated into the framework of MCF can significantly enhance the Lewis acidity of MCF. • The Ce-MCF support was synthesized by a pH-adjusting hydrothermal synthesis method with addition of citric acid.